Hudson, NY ADU Rules: No Size Cap, Allowed in Every District That Permits a Single-Family Home

By Spenser McCoy

The City of Hudson passed a new accessory dwelling unit law in August 2025, and the standout feature is what it doesn't have: a fixed maximum size. Instead of a flat square-footage ceiling, your ADU can be as large as the gross floor area of your existing house — with a 350 square foot floor. Build a bigger main house someday, and your ceiling for a future ADU grows with it.

Just as notable: ADUs are permitted in every zoning district in the city as an accessory to a one-family dwelling, not tucked away in a handful of residential zones. The unit can go inside your principal dwelling (including an attached garage) or in a separate accessory structure — but not in the front yard; it has to sit in the rear or side yard.

The tradeoff is a real owner-occupancy commitment. At the time you apply, the property has to be your primary residence, and after your certificate of occupancy is issued, you (or the ADU occupant) need to keep it that way — living in either the main house or the ADU — for a continuous 12 months. If your property sits in one of Hudson's historic districts, plan on one more step: a Certificate of Appropriateness from the Historic Preservation Commission before you build.

The bottom line: Hudson traded a flexible size cap for a firmer commitment to actually living there. If that's your plan anyway, this is one of the more generous codes in Columbia County.

FAQ What's the maximum ADU size in Hudson? There's no separate fixed cap — it's limited to the size of your existing house.

Do I have to live in the house to build an ADU in Hudson? Yes, for at least 12 continuous months after the certificate of occupancy is issued.

Are ADUs allowed everywhere in the city? Yes, in every zoning district, as an accessory to a one-family home.

Curious what your Hudson lot could support? Book a free Discovery Call with OneBuild today and we'll walk through the current rules with you.